[Historical foundations of the receptor concept in pharmacology]

In present-day pharmacology, the existence of specific cell receptors, which can combine chemically with drugs, poisons, neurotransmitters and hormones, is often taken for granted. However, until the 1960s receptors were controversial hypothetical entities. This article examines the initial experimental evidence for receptors that was produced and discussed between the 1870s and the 1930s. It is argued that pharmacologists were reluctant to adopt the receptor concept because of the indirect nature of the available experimental evidence, the competition with a physical theory of drug action and the fact that the idea of receptors had not originated from pharmacology itself, but from immunology and neurophysiology.